Multiagent Supervisory Control for Power Management in DC Microgrids

Abstract

This paper proposes multiagent supervisory control for precise power management in isolated dc microgrids. Two power management aspects are considered: 1) equal power sharing, which is realized via a proposed distributed equal power sharing algorithm; and 2) optimal power dispatch, which is achieved through a proposed distributed equal incremental cost (DEIC) algorithm. Both algorithms offer the additional advantage of the ability to restore the average system voltage to its nominal value. The proposed algorithms are based on the application of the average consensus theory along with voltage sensitivity analysis. Each distributed generation (DG) unit exchanges information with its neighbors, thus locally updating its no-load voltage setting to achieve the supervisory control objectives. The incorporation of DG droop-based control renders the proposed algorithms fully distributed with a reduced number of agents. The stability of the proposed algorithms is addressed, as well as the convergence of the proposed DEIC algorithm. Real-time OPAL-RT simulations demonstrate the effectiveness of the proposed algorithms in a hardware-in-the-loop application.

Overview of Real-Time Simulation as a Supporting Effort to Smart-Grid Attainment

“…Conclusively, RT is not directly subjected to its speed, but its predictability [30] (p. 8). Actually, it is a common engineering practice to test such proposals using models running in RT before testing over real conditions [9,32,33] as the dynamic consistency is guaranteed.…”

“…Likewise, an RT micro-grid was simulated in [9]; it was later controlled by a different RT system, which included multi-agent decision-making control. The main aim of the aforementioned work was to hierarchically manage the grid in a supervisory fashion.…”

“…This will obviously demand a modernized smart-city infrastructure requiring minimum human intervention [3] where the power grid becomes decentralized and an enabler of customer-side integration to the power flow [9]. The grid must be outwardly simple for customer integration in spite of internal sophistication [10].…”

Formulation and Analysis of an Approximate Expression for Voltage Sensitivity in Radial DC Distribution Systems

“…The denominator and the numerator in Equation (36) have similar values because of the assumption in Equation (24). In Equation (36), the backward term in the denominator is equivalent to the voltage difference between the slack bus and bus i, which is induced by the bus real power at bus i, which should be significantly smaller than the bus voltage.…”

“…The calculated voltage sensitivity could be utilized for voltage control. Voltage control method based on multi agent system (MAS) has been reported and voltage sensitivity is utilized [23,24]. In these researches, agents calculate voltage sensitivity factor from the inverse of the Jacobian matrix for active power control of DERs and such process could be simplified using proposed formulation to reduce calculation efforts.…”